[flang] When formatting integers for Gw.d/Gw.dEe output, only 'w' matters

Leading zeros should appear only for Iw.m output formatting.
Gw, Gw.d, and Gw.dEe output editing all map to Iw with no ".m"
(Fortran 202X 13.7.5.2.2).

Differential Revision: https://reviews.llvm.org/D159037